Lamp casings for projectors



June 14, 1955 Filed Oct. 25, 1951 W- KRAUSKOPF LAMP CASINGS FOR PROJECTORS 2 Sheets-Sheet l June 14, 1955 Filed Oct. 25, 1951 W. KRAUSKOPF LAMP CASINGS FOR PROJECTORS 2 Sheets-Sheet 2 United States Patent 6 LAMP CASINGS FOR PROJECTORS Wilhelm Krauskopf, Kiel, Germany, assignor to Zeiss Ikon A. G., Stuttgart, Stuttgart, Germany Application October 25, 1951, Serial No. 253,037

8 Claims. (Cl. 240-41) doors when opened result in a very rapid cooling of the heated internal parts, particularly of the reflector mirror, because the opening of these walls and flap doors create a chimney effect, namely, a strong current of cold air enters the lamp housing and rises to the top of the housing and outwardly through a vent or the like. Furthermore, flap doors or removable walls are very inconvenient, because much space is required for tilting the doors or putting the removed walls aside.

More suitable is a sliding door which in accordance with certain constructions has the shape of a circularly curved longitudinal wall of the lamp casing and is guided with its side edges in correspondingly curved guide rails mounted on the end walls of the housing. When such a door is opened and moved upwardly, it covers the upper vent in the casing and therefore prevents the creation of cold air current passing through the heated interior of the lamp housing. However, such a slidable door requires the employment of stationary guides which are circularly shaped. Furthermore, there is to be considered that the sliding door in its open position covers the opposite side wall of the lamp housing at least partially. At least the door has to be arranged in such a manner that it moves along the inside of the opposite side wall. Since, furthermore, the lamp casings and doors are usually provided with double walls, it is necessary that the doors when guided properly in stationary circularly curved guide rails will have a certain unsymmetric shape which is not at all very flattering to the appearance of the lamp housing.

It is an object of the present invention to provide a lamp casing for picture projectors with a sliding door which is moved in a guide arranged on the end walls of the lamp casing and which guide the door past the upper part of the housing and along the opposite side wall Whereby the door has a curvature which is different from the well-known circular form of the guide.

Another object of the invention is to provide suitable means for obtaining this effect by providing guides and links for controlling the movement of the door. One embodiment of the invention consists of a door which by means of pins, preferably arranged on the corners of the door, are guided in suitable curved guide rails.

It is also an object of the invention to provide a sliding door with links so that the slidable door may also be pivotally moved during its opening and closing movements. These links may be provided together with other guiding means in such a manner that the door by means of lateral pins is supported at its upper ends while the bad lower end of the door is connected with pivotally mount ed links.

It is also an object of the invention to provide the slidable door with such a shape that the same corresponds to the shape of the lamp housing, which last named shape may have any desired form without being bound by the particular guiding movement of the door. The door may form a part of the housing, it may have a suitable curvature which is the same as one of the housing walls. The lamp housing may have in cross-section a rectangular or circular shape and may have a height which is greater than its width and may also have an oval shape. The slidable door is controlled during its movement by guides which according to the invention are mounted on the front and rear end Walls of the lamp housing. The new guide for the door may be employed in connection with all desired shapes of the lamp housing.

The invention will be better understood from a consideration of the following description in conjunction with the accompanying drawings in which the figures illustrate the two preferred embodiments of the invention.

In the drawings:

Fig. 1 illustrates a side elevation View of a picture projector with a portion in section;

Fig. 2 illustrates diagrammatically a cross-sectional view on the line II-II of Fig. 1;

Fig. 3 illustrates diagrammatically a cross-sectional view of another embodiment of a door and its guide for a picture projector; and

Fig. 4 is a side elevation view of the door employed in the embodiment of Fig. 3.

Referring to Figs. 1 and 2, the slidable door 1 forms one of the longitudinal side walls of the lamp housing and is arranged on that side on which the operator is stationed to operate the projector. The door is circularly curved and the center of curvature is coincident with the center axis M of the lamp housing which axis at the same time forms the axis of the light beam produced in the lamp housing and passing axially through the objective of the projector. The other side wall or rear wall 2 of the lamp casing is curved similarly to the door 1 and may be arranged so as to be detachable from the housing. The lamp housing along its entire circumference is provided with a double wall for the purpose of preventing 1 excess heat radiating and for the purpose of forming an air circulating system. The doubled wall slidable door 1 forms a part of the housing wall. For the admission of circulating air there are provided the apertures 3 at the lower portion of the outer panel of the door 1 and the outer panel of the opposite rear wall 2 while apertures 4 at the upper portion of the outer panel of the door and the upper portion of the outer panel of the rear wall 2 conduct the air between the inner and outer wall panels into the inner and outer housing domes 5 and 6 and finally into the chimney 7 outwardly.

For guiding the slidable door 1 there are provided on the inner faces of the front and rear end walls 8 and 9 of the housing the guide rails It). The slotted ends of pins 11 which are mounted on the edges of the door extend into these guide rails 10. The pins 11 are rotatable and slidably arranged on the four corners of the slidable door 1. For the purpose of attaching the door or inserting the same in the guide rails 10 and for removing the doors if desired from the housing, the pins 11 may be 1' withdrawn from the guide rails 10 against the action of springs 12 mounted in individual casings 12a at the corners of the door. The springs 12 rest with one of its ends against collars 11a on the pins 11. The guide rails 10 are curved in such a manner that their point of curvature is coincident with the center axis M of the housing for that portion which extends along the side walls, but as soon as these guides extend across the upper portion of the housing and across the chimney 7 toward the rear walls they are curved in such a manner that the slidable door when moved to open position moves past the housing dome 5, 6 and rearwardly along the inner face of the rear Wall 2 Without engaging the latter. The slidable door 1 can be moved upwardly until the handles 13 on the door engage the upper edge of the door opening provided in the housing.

The Figs. 3 and 4 illustrate a somewhat modified arrangement of the slidable door. According to these figures, the door In engages with pins 14 provided at the upper corners of the door in straight guide rails 15. The lower portion of the door, however, by means of a link 16 having the shape of a yoke is pivotally mounted at 21 to parts of the end walls of the housing. The straight guide rails 15 are somewhat angularly bent at their front ends as shown at 17 and guide the door in such a manner that the edges of the same, when closed, are flush with the adjacent walls of the housing.

The angularly bent end portions 17 of the guide rails also serve the purpose to hold the door, when the same is closed and is positioned substantially vertical, rather tightly closed so that a certain amount of force is required to open the door before it may be moved with its pins 14 easily into the straight portion of the guide rails 15. Furthermore, the other rear ends of the straight guide rails 15 are likewise provided with angularly bent portions 18 to form a kind of a brake for holding the door securely in the upper open position which is indicated in dash and dotted lines.

In the last shown embodiments, the cross-sectional shape 19 of the lamp housing is not circular as shown in the first embodiment, but it has more of a shape of a rectangle resting on its small side. The side walls of the lamp housing are only slightly curved outwardly so that also the slidable door 1 has only a slight curvature. In this last named embodiment the illustrated combined slide and link suspension for the door 1a is preferred.

If necessary or desired, the slidable door In may be guided solely at its upper end by the pins 14 and the rails 15, whereby the sides of the door opening may be provided with bars which prevent a swinging of the door into the housing proper when the door is opened or closed. The mentioned link 16 may also be provided at the upper end and is not limited to the lower end.

Furthermore, means may be provided for compensating the weight of the slidable door while being moved into its open or closed position. According to Figs. 3 and 4, there is provided an angular spring 20 coiled around that portion of the link 16 which forms the pivot axis with the housing. This spring 20 engages with one end a portion of the link at 23 and with the other end engages an anchored pin 24' on the end wall of the housing.

What I claim is:

I. In a lamp housing for picture projectors, a chimney forming a vent extending outwardly from the upper portion of the housing, a slidable door forming one side wall of said housing and slidable in an arc-shaped path extending transversely about the longitudinal axis of the housing, said housing having vertical end walls provided with guide rails for said slidable door, and guide pins extending outwardly from the side edges of said door and engaging said guide rails, said guide rails being areshaped and so positioned on said end walls to guide the slidable door when opened along the inside of the other opposite side wall of said housing, said door in its open position covering the vent formed by said chimney in the upper portion of said housing.

2. In a lamp housing for picture projectors having a vent in the top wall thereof, a reflector at one end of said housing and an access opening in the side wall, a slidable door for said access opening forming one complete side wall of said housing, guide rails on the end walls of said housing for guiding said slidable door along an arcuate pathway and upwardly and inwardly toward the opposite wall of said lamp housing, said guide rails extending across the upper portion of the housing toward the other side wall to support the slidable door in the upper portion of the lamp housing when in an opened position and thereby obstruct air passage through the access opening and vent when said slidable door is in its open position, said guide rails being arranged to support said slidable door in its closed position, and pins on at least one end of said door for being received in said guide rails.

3. A lamp projector according to claim 2 in which said guide pins extend outwardly from the side edges of said door for being received in said guide rails, said guide rails being arch-shaped and so positioned on said end walls to guide the slidable door when opened along the inside of the other opposite side wall of said housing.

4. A lamp projector according to claim 2 in which the guide pins extend outwardly from the upper side edges of said slidable door and engage within said guide rails, and pivotally mounted link means connecting said end walls with the lower portion of said slidable door to control the sliding movement of the latter.

5. A lamp projector according to claim 2 in which the guide pins extend outwardly from the side edges of the door and engage within said guide rails, said guide rails being provided with angularly bent end portions to serve as means for arresting said slidable door in its completely open and closed positions.

6. A lamp projector according to claim 2 in which said guide pins extend outwardly from the side edges of said door and engage within said guide rails, said guide rails being so positioned on said end walls to guide the slidable door when opened into a substantially horizontal position in the upper portion of said housing, said guide rails being provided with angularly bent end portions to serve as means for arresting said slidable door in its completely open and closed positions.

7. A lamp projector according to claim 2 in which said guide pins extend outwardly from the upper ends of the side edges of said slidable door and engage said guide rails and pivotally mounted link means connecting said end walls with the lower portion of said slidable door to control the sliding movement of the latter, said guide rails being straight and being provided with angularly bent end portions to serve as means for arresting said slidable door in its completely open and closed position.

8. A lamp projector according to claim 2 in which said guide pins extend outwardly from the upper ends of the side edges of said slidable door and engage within said guide rails, pivotally mounted link means connecting said end walls with the lower portion of said slidable door to control the sliding and pivotal movement of the latter, and spring means operatively connected with said link means to serve as means for counter-balancing the weight of said slidable and swinging door.

References Cited in the file of this patent UNITED STATES PATENTS 

